Characteristics of Dewatered Sewage Sludge and Green Waste Co-composting

The purpose of this work is to study the characteristics of the co-composting of sewage sludge and green waste (weight ratio 8:1). The indexes such as temperature, total nitrogen and total organic carbon contents, germination index, were analyzed to examine the feasibility of co-composting of sludge and grass. It was found that the composting temperature met the requirement of 55°C for 3 days during the composting process. The total nitrogen and total organic carbon contents reduced from 14.3 to 7.2 mg/g and from 217.1 to 164.4 mg/g, respectively, and the seed germination index reached 120.4% after 17 days of composting, indicating that the toxicity had been eliminated, and the compost tended to be stabilized. The maturity period of primary fermentation for thermophilic aerobic composting of sewage sludge and grass can be defined as 14 days.